Scotland K. et al., 2019: Total Surface Area Influences Stone Free Outcomes in Extracorporeal Shock Wave Lithotripsy for Distal Ureteral Calculi
Scotland K, Safaee Ardekani G, Chan J, Paterson R, Chew BH.
Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
Current American Urological Association guidelines recommend ureteroscopy as primary management of distal ureteral stones and shock wave lithotripsy (SWL) as a secondary option. Utilization of SWL in the management of nephrolithiasis in North America has decreased. We hypothesized that SWL continues to be an effective option in the management of distal ureteral calculi and studied data from our center in patients who received SWL for distal ureteral stones. METHODS: A retrospective review was performed of 104 patients treated initially with SWL for distal ureteral calculi between 2011 and 2018 at this institution. The success rate of SWL was assessed via radiologic imaging and if subsequent procedures were required to render patients stone free. RESULTS: Operative note and chart review identified 104 patients who presented with distal ureteral stones and were treated with SWL as the initial form of management. Average patient age was 52.2 ± 15.3 years, average BMI was 27.4 ± 5.7 and average total axial stone surface area was 25.96 ± 14.32 mm2. Of these patients, 78.8% (n=82) were stone free following one SWL and required no subsequent procedures. 87.5% (n=91) were stone free following a second SWL and 87.5% (n=91) were stone free following a secondary URS. After the initial SWL, residual stones were identified in 21.2% of patients (n=22). Four patients, 3.8% required a salvage ureteroscopy following a failed second SWL to achieve stone-free status. CONCLUSION: One SWL procedure offers a stone free rate of 78.8% and after 2 SWLs, an 87.5% stone free rate. Only 12.5% of patients undergoing SWL at our centre required ureteroscopy to achieve a the stone free status. SWL is an effective modality in the treatment of distal ureteral stones.
J Endourol. 2019 Mar 12. doi: 10.1089/end.2019.0120. [Epub ahead of print]
It is nice to read that ESWL is regarded and proved to be an excellent and unjustly forgotten treatment modality.
The abstract somehow tells only half of the story; in the method section it says: “Electronic Medical Records at Vancouver General Hospital were queried for patients who presented with distal ureteral stones and underwent SWL between Jan 2011 and October
2018. A total of 104 patients were identified for this study. Patients in the study included those for whom SWL was performed as an urgent procedure upon presentation with colic and those treated after failure of medical expulsive therapy. Asymptomatic patients underwent medical expulsive therapy for 1-3 months prior to SWL.”
This is a report from the major hospital in Vancouver. 104 patients with lower ureteral stones in nearly 8 years is a small group and the selection of patients is very exceptional: “SWL was performed as an urgent procedure upon presentation with colic and those treated after failure of medical expulsive therapy”. How many patients at the same time period underwent primary URS with equivalent, better or worse results is not indicated. It seems that this is a highly selected group of patients.
As to the secondary procedures the authors unfortunately failed to give hints why and how they selected the patients for a successful second ESWL; it is only retrospectively and statistically that they could show that stone density and stone-to-skin distance had no influence but stone surface calculated by the CT data had: “In the 22 patients with residual stones, nine (8.7% of total) underwent a second SWL, nine received a URS, and four (3.8% of total) required a salvage ureteroscopy following a failed second SWL to achieve a stone free status (Fig. 1-2). In total, 12.5% (n=12) of patients received a second SWL and 12.5% (n=12) received a URS in this study. Three patients presented with flank pain after an initial SWL procedure. Two were managed with pain medicine; the remaining patient was found to be obstructed on workup and underwent URS with stent placement.”
We need more publications like this with better background information to put ESWL into its proper position.